Mongol invasion of Rus

The Mongol invasion of Rus occurred from 1223 to 1242 when the Mongol Empire invaded the Kievan Rus states in Russia, Ukraine, and Belarus. The Mongols forced the Russian principalities to become their vassal states, and they established the Golden Horde.

Background
In 1223, after ravaging Georgia, the Mongol generals Jebe and Subedei crossed the Caucasus and defeated a coalition of local tribes before sacking Astrakhan. The Mongols now found themselves on familiar flat terrain with several villages to pillage; Jebe travelled to wards the Dnieper River with his army, while Subedei split off and headed towards the Crimea. He allied with the local Venetian trading post there, promising to destroy any non-Venetian colonies in the area. He attacked and razed Soldaia in exchange for the Venetians giving the Mongols information on the kingdoms of Europe.

Great Raid
Meanwhile, the surviving Kipchaks fled and informed the Kievan Rus princes of their plight. The Rus principalities united into one alliance with a combined army of 60,000 troops, mainly cavalry, so the Mongols united into one army and sent ambassadors to the Rus princes and asked them to stay out of the conflict as they destroyed the Kipchaks. The princes angered the Mongols by killing the envoys, and the allied army met the Mongols on the banks of the Dnieper River. Subedei sacrificed his rearguard of 1,000 troops while the rest of his army hastily crossed the river and retreated. The Kipchaks pressured the Russian princes to pursue the Mongols, who left behind loot, prisoners, and livestock to deceive the Russians into becoming overconfident. The Kipchak vanguard soon outran the Russians and met Subedei's army in the Battle of Kalka River. Subedei's lancers defeated the Kipchaks before slowing the Rus advance with arrows and outflanking them. Mstislav III of Kiev rallied his 10,000 troops to fight the pursuing Mongols, but the Mongols surrounded his position for three days, showering his men with arrows and smoke bombs. They were forced to peacefully surrender, but they were attacked as soon as they left their camp. Only a tenth of the allied army avoided death or capture, and the Rus nobles were tied up and placed beneath a wooden platform on which the Mongols feasted as the Russians were crushed beneath them. Subedei then crossed the Caspian Sea and defeated more Kipchaks and Volga Bulgars on the way back to Mongolia, ending his great raid.

After Genghis Khan's death in 1227, his successor Ogedei Khan sent Batu Khan with a large army to conquer Europe. By 1237, Volga Bulgaria was conquered, and Crimea and the lands of the Kipchaks and Alans were next. By the end of 1237, all lands to the east of the Don River were in Mongol hands. Batu then sent envoys to Yury II of Vladimir to demand his allegiance, and, in 1238, the Mongols razed Vladimir and destroyed several other Rus princedoms and razed theri capitals. The Mongols never allowed the Rus to unite their forces, and the only major cities to evade destruction were Novgorod and Pskov, which accepted Mongol authority. By 1239, the Mongols returned beyond the Don. Batu sent his forces south to help conquer the Caucasus while Mongke and his forces were recalled to Mongolia, and, in the summer of the same year, the Mongols besieged Kiev, the most prosperous Rus city. The city fell after three months, and all 50,000 locals were massacred in retribution for the execution of Mongol diplomats. The Mongols now looked towards Central Europe, backed by the Venetians, who provided them information on Europe.